Diagnostic evaluation of unilateral diaphragmatic paralysis

CT: computed tomography; FVC: forced vital capacity; MIP: maximal inspiratory pressure; EMG: electromyography; Pdi: transdiaphragmatic pressures; PNCS: phrenic nerve conduction studies.

* The sniff test is the most helpful diagnostic test during the initial evaluation. While most commonly performed using fluoroscopy, there is growing expertise in using ultrasonography for the sniff test.

¶ Occasionally, the MIP can be normal, and the diagnosis may be made without this feature, particularly if the patient has no symptoms.

Δ Significant clinical judgement is generally required when deciding to proceed with such testing (eg, unexplained symptoms, patient desire for a diagnosis, differentiating the contribution of paralysis to symptoms, patients with suspected bilateral involvement).